by Deirdre Shesgreen, Gannett Washington Bureau

by Deirdre Shesgreen, Gannett Washington Bureau

WASHINGTON - Republican Sen. Rob Portman said Thursday that he now supports gay marriage - a surprise turnabout on a hot-button social issue, sparked by a deeply personal reflection that began two years ago after Portman's son, Will, told him that he is gay.

"It's a change of heart from the position of a father," Portman told three Ohio reporters on Thursday during a 45-minute interview in his office. "I think we should be allowing gay couples the joy and stability of marriage."

Portman's endorsement of gay marriage makes him the only sitting Republican senator to hold that position. But it comes at a time when public attitudes are shifting quickly on the issue, and more and more states are sanctioning gay marriage.

Ohio's junior senator outlined his position in the interview, and in an op-ed that appears Friday in The Columbus Dispatch.

"I have come to believe that if two people are prepared to make a lifetime commitment to love and care for each other in good times and bad, the government shouldn't deny them the opportunity to get married," Portman writes in the op-ed. "This isn't how I've always felt."

Portman said his own evolution on the issue began in 2011, when Will, then a freshman at Yale University, made a stunning revelation.

"Will â?¦ came to Jane and me and announced that he was gay, that it was not a choice. It was who he is and he had been that way since he could remember," Portman recalled of the conversation. "Jane and I were both surprised, very surprised, but also very supportive of him. Our reaction was not about policy or positions. It was about him as a son and letting him know we were 110% supportive of him."

His son's homosexuality "allowed me to think about this issue from a new perspective, and that's as a dad who loves his son a lot," Portman said. He said he wants Will to have the same chance at an enduring relationship, "like Jane and I have had for over 26 years."

Portman - who until now said marriage should only be between a man and a woman - said it took him "a while" to make the political shift and "get comfortable" supporting gay marriage.

Portman was among those who, as a member of the House in 1996, voted in favor of the Defense of Marriage Act (DOMA), which defines marriage as between a man and a woman and bars federal recognition of same-sex marriage. It also says states can't be forced to recognize a same-sex marriage performed in another state. Portman also voted in favor of a constitutional amendment to ban gay marriage when he was in the House.

"Rob believes marriage is a sacred bond between one man and one woman," Portman's spokesman told The Cincinnati Enquirer in 2011. At the time, Portman was the target of a protest by University of Michigan Law School students. He had been invited to deliver the school's commencement address, but nearly 300 students, angry about Portman's opposition to gay rights, asked the school to revoke the invitation.

On Thursday, Portman said he would like to see Congress repeal the provision of DOMA that bans federal recognition of same-sex marriage, although he still supports the part of the law that says states should not be forced to recognize same-sex marriages.

"I'm of the view that the states ought to be deciding this issue, and frankly that's happening increasingly," Portman said.

Portman, who is Methodist, said he did not come to this new position easily or quickly. He talked to his pastor and other religious leaders. He talked to his family, friends, and political allies. He talked to those who support gay marriage, including former vice president Dick Cheney - as well as those who do not, including Senate Minority Leader Mitch McConnell, R-Ky.

"I have had a process and a journey," he said. "I've done a lot of reading. I've done a lot of talking to folks."

Asked whether he would support overturning Ohio's state ban on same-sex marriage if it comes up in a voter referendum, Portman said yes.

"I'm going to be supportive of Ohioans having the opportunity to marry," he said. "I would not plan to take a leadership role in this, but people will know my position."

Other Republicans have similarly embraced same-sex marriage. For example, more than 80 prominent Republicans - including ex-governors, former members of Congress and veterans of the George W. Bush administration - are planning to file a "friend of the court" brief asking the U.S. Supreme Court to strike down California's Proposition 8, which banned same-sex marriage.

The signers include former governors Jon Huntsman of Utah, Christine Todd Whitman of New Jersey, and William Weld of Massachusetts.

But many Republicans in Congress, including House Speaker John Boehner, remain fiercely opposed to same-sex marriage. And the issue ignites strong passions among social conservatives, a key base for Portman in Ohio.

Portman said Will, who is now 21, nudged him to change his views and wanted him to publicly declare his support for gay marriage. "He hasn't pushed me, but he's been encouraging, and he's been very much involved," he said.

Portman said his previous views on marriage were rooted in his faith. But "the overriding message of love and compassion that I take from the Bible . . . and the fact that I believe we are all created by our maker . . . that has all influenced me in terms of my change on this issue," he said.

Portman said he concluded that marriage as an institution would be strengthened by allowing gay couples to wed.

"When two people make a commitment to one another, it can actually enhance the institution of marriage," he said.

Even as he endorsed same-sex marriage, Portman said this would not suddenly become a top legislative priority for him. He has no plans, for example, to introduce legislation to repeal elements of DOMA or take on any other gay rights issues.

"I'm kind of an economic policy wonk," he said. "That's how I got into this business. That's been my priority and my focus, and it will continue to be."

Portman said he wanted to announce his position now, in part because the Supreme Court will hear arguments on DOMA later this month.

"I felt it was important to let my constituents know where I stand because these court cases are going to encourage members of the media to ask senators and House members what their position is," Portman said, adding that he wanted "to do this before the politics of these court decisions . . . makes it more difficult maybe to have an honest discussion."

Portman said he's told some of his Republican colleagues about his shift and all of them have been very "respectful" of his decision, even if they don't agree.

He consulted Cheney, whose daughter is gay, about the issue last weekend, when they were both attending a conference. "His advice was 'Do the right thing. Follow your heart,' " Portman said.

Asked how this might affect his political career, Portman, who has been touted as a possible 2016 presidential candidate, said he had no idea.

"That has nothing to do with my decision," he said. "This was personally and family initiated, and then it was a process of carefully thinking through the issue."